Screen assemblies that are used in boreholes typically involve a perforated base pipe that has opposing connections for joining to a tubular string. The connections are likely threaded. The filtering media can be in different formats such as a continuous wire having a predetermined cross-section wound around circumferentially spaced and axially oriented members and spot welded to the axial members at intersections with the wound wire. Various weaves of wire are also known and used in such applications. These screen material feature a grid pattern of interwoven metal wires one example of which is a Dutch twill. To protect the one or more filtering layers that are mounted over the base pipe there is an outer shroud that is used. The shroud protects the filtering layers from damage on the way into the hole and features an ordered pattern of holes or rows of louver type openings made by punching through the material that comes in strip or sheet form. Such sheets or strips have been reformed into cylindrical shapes by being spiral wound and having the spiral seams welded. Welding spirally wound material after forming it into a cylinder shape whether using a single or multiple parallel wound strips is shown in US2007/0199973 and US 2007/1199889. Overlying layers and spirally winding them together followed by seam welding the outer layer is shown in U.S. Pat. No. 7,287,684 FIG. 6. Making layers of nested cylindrical shapes for the screen assembly and outer shroud and then assembling them to each other and inserting a mandrel and running the assembled components through a die to get a desired exterior dimension is shown in U.S. Pat. No. 8,127,447. The problem with the latter design is that it was difficult to get a desired finished exterior dimension on the assembly and controlling that dimension was important because the assembly has to pass through drift dimensions downhole without binding. Another issue with the pulling the assembly through a die was that the layers were pushed tightly together and against the base pipe. Frequently one or more drainage layers had to be omitted to insure that the desired exterior dimension could be obtained.
What was needed and is provided by the present invention is a method to assemble a screen assembly by taking the layers when they are laid flat as strips and joining an outer to an inner layer with a screening layer trapped in between followed by spiral rolling the assembly and seam welding or otherwise closing a spiral seam on the exterior. These and other aspects of the present invention will become more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings with the understanding that the full scope of the invention is to be determined by the appended claims.